The lips, tongue, velum and glottis can be positioned in different ways to produce different sound types.
These various configurations are called the manners of articulation.
Oral Vs Nasal Phones
A basic distinction in manners of articulation is between oral and nasal phones.
When the velum is raised, cutting off the airflow through the nasal passage, oral sounds are produced.
Nasal sounds are produced when the velum is lowered to allow the passage of air through the nasal passage.
Both consonants and vowels can be nasal – in which case the phones are generally voiced.
Obstruents & Sonorants
In phonetics, an obstruent is a consonant sound formed by obstructing the airway.
Obstruents are subdivided into:
plosives
fricatives
affricates.
In phonetics and phonology, a sonorant is a member of a class of speech sounds that are continuants produced without turbulent airflow in the vocal tract:
Vowels
approximants
nasal consonants
Stops & Plosives
Stops and plosives are made with a complete and momentary closure of airflow through the vocal tract, thus preventing the escape of air.
Usually, the term plosive is reserved for oral (non-nasal) stops: i.e. stops with a release burst.
In the world’s languages, stops are found at the following points of articulation:
bilabial
dental
alveolar
retroflex
palatal
velar
uvular
glottal
Classification of Stops
Stops may further be classified depending on the following properties:
nasalization
voice
aspiration
length
airstream mechanism
tenseness
Nasalization
Nasal stops are differentiated from oral stops by the lowered velum that allows air to escape through the nose during articulation
Acoustically nasal stops are sonorants, as they have a non-turbulent airflow and are nearly always voiced
but in terms of articulation, they are obstruents, as there is a complete blockage of the oral cavity
Nasal Stops in English
Although nasal stops may occur at most places of articulation, English has only a few
While nasal stops may be either voiced or voiceless, they are typically voiced in most human languages
Bilabial nasal stops – [m] entail complete closure between the lips, voicing and escape of air through the nasal cavity
e.g. [m] in map
Labio-dental nasal stops – entail complete closure between the lower lip and upper teeth, voicing and escape of air through the nasal cavity
e.g. 
in pamphlet – 
( or 
In English labio-dental nasal stops occur before labio-dental sounds and is a reflection of the process called assimilation (which we will talk about in a later session)
Dental nasal stops – entail complete closure between the tip of the tongue and the upper teeth, voicing and escape of air through the nasal cavity
e.g. 
in tenth – 
Alveolar nasal stops – [n] entail complete closure between the blade of the tongue and the alveolar ridge, voicing and escape of air through the nasal cavity
e.g. [n] in not – 
Velar nasal stops – entail complete closure between the back of the tongue and the velum, voicing and escape of air through the nasal cavity
e.g. 
in sing – 
Voice
Voiced stops are articulated with vibrations of the vocal cords
Voiceless stops are articulated without vibration of the vocal cords.
In English, plosives are usually voiceless, whereas nasal stops are mostly voiced
Aspiration
Aspirated sounds are those where the vocal cords begin to vibrate later than the release of the stop
A stronger puff of air is felt on articulation of an aspirated stop
e.g. [p] in pit
spit
Aspirated stops are transcribed with an aspiration diacritic – 
e.g. in 
pit 
Length
Some languages differentiate between ‘normal’ stops and long stops – geminates (which may last up to three times as long as the short stops
However, English does not mark such a distinction in stops (or any other consonants)
Airstream mechanism
Stops may be made with more than one airstream mechanism. The normal airstream mechanism for producing stops is pulmonic egressive, that is, with air flowing outward from the lungs.
However, it is possible to make stops with more than one airstream mechanism
All languages have pulmonic stops
Some languages have stops made with other mechanisms as well:
– ejective stops (glottalic egressive)
– implosive stops (glottalic ingressive)
– lick consonants (velaric ingressive)
Tenseness
Tenseness is a mark of the degree of muscular constriction of the glottis.
Although English does mark a distinction between tenseness and laxness in vowels, consonants are not differentiated on this basis.
Plosives & Stops in English
The Plosives and stops in English are:
i. voiceless bilabial plosive – [p]
ii. voiced bilabial plosive – [b]
iii. voiceless alveolar plosive – [ t]
iv. voiced alveolar plosive – [d]
v. voiceless velar plosive – [k]
vi. voiced velar plosive – [g]
vii. glottal stop – 
(not marked as a phoneme in most dialects of English)
viii. bilabial nasal stop – [m]
ix. alveolar nasal stop – [n]
x. velar nasal stop –
Although the following distinctions may be used in speech, English does not mark them as distinctive phonemes.
– labio-dental nasal stop –
– dental nasal stops –
